Modified polymers that are modified by a compound containing a nitrone group (nitrone compound) have been known conventionally as polymers contained in rubber compositions for use in tires and the like.
Patent Document 1, for example, describes “a rubber composition comprising, per 100 parts by weight of a diene-based rubber containing from 5 to 100 wt. % of a modified butadiene rubber, from 10 to 120 parts by weight of silica; wherein the modified butadiene rubber is butadiene rubber with a cis-content of 90% or greater modified by a nitrone compound having a nitrogen-containing heterocycle per molecule (Claim 1).” Additionally, Patent Document 1 describes modification by a nitrone compound causing heat build-up to decrease (paragraph [0006] and the like). Note that lower values of tan δ (60° C.), which is the loss tangent (loss coefficient), are indicative of low heat build-up and low rolling resistance.